It is well known that the transmission of electromagnetic energy through a waveguide may introduce the propagation of several modes of electromagnetic waves. The physical dimensions of the waveguide determine the dominant mode. For example, the TE10 (transverse electric) mode is the dominant mode in a rectangular waveguide. The TE signifies that all electric fields are transverse to the direction of propagation and that no longitudinal electric field is present. If the frequency of a communicated signal is above the cutoff frequency for a given mode, the electromagnetic energy may be transmitted through the waveguide for that particular mode with minimal attenuation. Therefore, it may be desirable in many instances to avoid operating an electromagnetic wave energy system near the lower cutoff frequency due to a dramatic attenuation at that point.
Known beam-forming antennas do little to filter E-plane edge currents on the beam-forming antenna. Consequently, surface electromagnetic waves may be supported and are propagated with the polarized electromagnetic signal. This may result in unwanted noise or undesirable electromagnetic sector patterns. A need exists for beam-forming antennas to eliminate E-plane edge currents and to minimize the propagation of surface electromagnetic waves. A further need exists to balance hybrid modes of the dominant mode which may result in clearer and more symmetrical electromagnetic wave energy for communications purposes.
It is therefore an object of the disclosed subject matter to present a novel beam-forming antenna that eliminates edge currents and creates an electromagnetic signal with symmetrical radiation patterns.
It is also an object of the disclosed subject matter to present a novel method of filtering electromagnetic wave energy by propagating electromagnetic wave energy to a beam-forming antenna, passing the energy through the beam-forming antenna and forming a capacitive surface reactance so that surface waves cannot be supported on the beam-forming antenna.